It is conventional to supply an air fuel mixture into an internal combustion engine by using an air stream passing through a constriction in which fuel is drawn into the air stream by reason of the vacuous effect caused by such constriction.
It is known to provide means by which the degree of constriction can be varied for instance by using the vacuous effect itself to draw the constricting members against resilient retention into a greater or lesser constricting effect.
I have discovered that substantial improvement in both economy of fuel usage for a given output of engine and furthermore some increased output of engine performance while achieving such fuel economy can be achieved at least in certain instances by use of a particular arrangement and it is therefore the object of this invention to propose an arrangement for controlling of carburation for an internal combustion engine which provides an advantage either in relation to economy or in relation to engine performance and in some instances and indeed as a result of improved engine performance improvements relating to pollution content of the exhaust.